!! Help with MBC !!

[wishnfor4g63T]

Okay so i've hit just about every thread on here related to mine and i've done everything listed. It's hard to say if i have missed a few threads so Please read my problem and give me an answer!!! i'll send you a Happy Meal!

...So i Have 2 MBC's one off ebay which had worked fine with my T-25 and another from a friend that looks like a Joe P. Regaurdless of where i install the mbc (to the bov or J pipe) i still get 10 PSI. Running the wastegate freely gave it the wonderfull 30 pounds and up on the boost gauge so i know the wastegate is not stuck.

I'm starting to have this feeling i'm going to have to drill the turbo like the t-25 and tap it. As far as i'm concerned if that means it will work i'll do it . BTW i don't know if this is a dumb thing to add but when i tapped my J pipe i left half the tubing in the pipe so it's like half in the pipe and half sticking out so i could put the hose on the end. I didn't know if this would make it hard to get the air to the MBC but maybe i just answered my own theory. What doesn't make sense is that the BOV line boosts to 10 also with a lil spike.

Well if anyone can help or has had the same problem i would greatly appreciate it. BTW this is a Slowboys Big 16g ported and polished with bigger turbine. I still have around 10 more days of warranty on it so i can send it back if anyone thinks it's turbo related. Thanks for any and all help!

 

[wishnfor4g63T]

Turning the screw Counter Clockwise aka screwing it out gave it more air flow. While screwing it in gave it less. I traded out springs with another pin that was a lil more longer and screwing it halfway stopped all air flow. I hope that answers your question Oldman sorry i didn't catch on.

I'm starting to believe maybe both of the mbc's are bad. The Joe p was given to me from a friend and on his 1g dsm he said it spiked to 22 psi then held at 12 if i remember right.

If no answer fixes my stupid boost problem by at least Wensday i'm going to order a boost controller preferably under 65$ recommended by you guys. Then have it installed by someone else that knows what their doing. I thought i knew what i was doing but maybe i am just losing my hope on this thing . Wish i could just slap my wastegate from the t-25 on it :-( i want to know what the deal is!

Thanks guys for the help! Your really keeping me busy =)

 

[oldman]

Isn't that essentially what you are looking for oldman? So that CCW right?

And that would be the wrong direction so I wanted to hear it from him, his answer wasn't clear if that was the direction in which he was adjusting to increase boost. With a ball and spring MBC, completely opposite of the ebay knock off BLEEDER mbc, the more you turn the knob in (CW), the more pressure you put on the spring to pit the ball against the inlet, the more pressure is required to push the ball out of the seat to release pressure to the wastegate side, the longer the wastegate stay shut, the higher the boost level you achieve. Go back and read post #9, all of this has been mentioned. The most difficult thing in trying to help someone troubleshoot on the internet is helping someone who "thinks they know" because they often don't follow directions and half of the time is spent in convincing them that "what they think they know" is wrong, it's always much easier to help someone who knows "NOTHING" to begin with.

His wastgate should be fine because a wastegate can only get stuck in 2 positions, opened or closed. If it was stuck opened, he would not be able to build any pressure, at least not until at least 6k rpm and it will be most 5-6psi. If it was stuck closed, he will build infinite amount of boost regardless if he has a MBC. This is why the problem here is MBC related as I have indicated in post #16.

Troubleshooting this kind of boost problem is a very simple process AS LONG AS the directions are followed exactly as written and questions are answered exactly as asked.

 

[oldman]

Turning the screw Counter Clockwise aka screwing it out gave it more air flow. While screwing it in gave it less. I traded out springs with another pin that was a lil more longer and screwing it halfway stopped all air flow. I hope that answers your question Oldman sorry i didn't catch on.

NO, that doesn't tell me which way you're turning it to increase boost, it just tells me which way gets more air and which way gets less which we already know. Are you turning it out to increase boost, YES or NO?

 

[wishnfor4g63T]

Are you turning it out to increase air, YES or NO? Yes, i turn the screw out to increase air.

When i use the MBC i started it in the middle. When i blow into the mbc with my mouth while turning the knob starting at the base counter clockwise. About the middle is where i started to get air flowing thru it and not just bleeding off. No matter how much farther i crank the screw out changes the psi.

Sorry, i really don't know much about the dsm's i'm really just getting started into them. Oldman do you think i should do a boost leak test?

 

[kenamond]

Are you turning it out to increase air, YES or NO? Yes, i turn the screw out to increase air.

When i use the MBC i started it in the middle. When i blow into the mbc with my mouth while turning the knob starting at the base counter clockwise. About the middle is where i started to get air flowing thru it and not just bleeding off. No matter how much farther i crank the screw out changes the psi.

Sorry, i really don't know much about the dsm's i'm really just getting started into them. Oldman do you think i should do a boost leak test?

Ugh. He didn't ask that! He asked, "Are you turning it out to increase BOOST, YES or NO?" Not "air". Please read and answer carefully and he'll get you set up in 2 posts or less.

 

[oldman]

Are you turning it out to increase air, YES or NO? Yes, i turn the screw out to increase air.

When i use the MBC i started it in the middle. When i blow into the mbc with my mouth while turning the knob starting at the base counter clockwise. About the middle is where i started to get air flowing thru it and not just bleeding off. No matter how much farther i crank the screw out changes the psi.

Getting more air = less boost, not more. Study my response in post # 27, if you don't understand any part of it, ask specific questions of what you don't understand, don't just skimp over it.

Sorry, i really don't know much about the dsm's i'm really just getting started into them. Oldman do you think i should do a boost leak test?

No problem, we all have to start somewhere, I was getting frustrated because "more air = more boost" was so deeply planted in your head that you were not reading or thinking about the content of my posts or else this problem would have been resolved in post #9.

A regularly done boost leak test is a must for a turbo charged vehicle, it's like asking if you should change your oil.

 

[wishnfor4g63T]

Ugh. He didn't ask that! He asked, "Are you turning it out to increase BOOST, YES or NO?" Not "air". Please read and answer carefully and he'll get you set up in 2 posts or less.

Yes i am turning it out to increase the boost.

I'm really not trying to make anyone mad! I'm trying to answer the questions correctly. On that question when i was posting i originaly thought he had put "increase airflow" so i was trying to match him to the T instead i put the wrong word...Sorry again.

 

[wishnfor4g63T]

OOHH!! so the less air going to the wastegate the more boost it will get. Wow, i thought the more the better. Okay, So when i blow thru both the mbc's and turn the knobs they work properly but when hooked up to the car they don't. This is where i think maybe a new mbc would be great start?

2ndly does it matter on the thickness of the vacume hoses? i've got some big and some small.

I'm really thankfull for all your help Oldman. If i'm starting to make you angry i apologize.

 

[oldman]

This is what you do, turn the knob IN (CW) until the point where air stop coming through, turn it IN (CW) another 1/2 turn and go for a test run, post back results.

 

[wishnfor4g63T]

I definitly will but it's late and i have to leave early in the morning for work. I'm more than confident now that it should work. If it doesn't i'm going to do a boost leak test and if that comes back good then i'm going to buy a brand name MBC. I'll post back monday around 5 eastern time and let everyone know how it went.

Thanks guys for all the help lets hope this is the end of my stupidty!

 

[kenamond]

I got my Joe P IL (in-line) MBC for like $50. I'm sure others could recommend others as well, but that's in your price range and is a reputable brand. And it's what I have

The MBC works by hiding the pressure signal (coming from the compressor housing) from the WGA. For a ball/spring, it blocks the air. For a bleeder, it bleeds it off. So for a ball/spring MBC, tightening it holds the ball harder against a hole, thus blocking air until higher boost. For a bleeder MBC, loosening it allows more air to bleed off, thus hiding more boost pressure from the WGA. Both result in higher boost.

So now you just have to fine-tune the MBC until your boost gauge reads the boost level you want to (and have supporting mods to) run.

 

[Talesin]

Try blowing into a boost gauge line sometime... generally you'll only be able to blow at around 5-7psi before your ears pop, usually a lot less. Meaning you could be blowing into the Joe-P as hard as you can with no air getting through, and the screw still would be too loose to build more than 10psi.

This is why we were asking about if you were using a ball-and-spring (which you tighten to raise boost, creating a restriction in the boost reference line to reduce the amount of boost the WG actuator will see), or a bleeder-type MBC (which you loosen to raise boost, reducing the boost reference the WG actuator sees by venting it to the outside air and giving you a nice little boost leak).


I picked up my Dejon MBC (ball-and-spring) from RRE for $50.

 

[ricktb]

From the pic it looks like the valve has been completely opened, or most of the way.. this would let air flow through the valve easier (or at a lower psi) and flow through to the wastegate actuator which would open at a lower psi, thus preventing more psi from building.. The way I understand it if you want a higher boost, you'd want to screw the valve down, so that a higher boost level can build before the MBC will let the air pass through to the wastegate.

Am I right oldman?

I also believe that blowing through the valve with your mouth can barely achieve 1 or 2 psi, so if you can blow through it freely with your mouth its probably opened to far already, just my 2 cents.

My MBC is a bleeder type valve and I set it close to all the way closed, like 3 turns from being closed fully. This gives me a nice 13psi of boost. If I open the valve I get less boost, if I close the valve I get more. No more than 15psi and no less than 10psi when taken to the extreme opened and closed positions. Dunno if thats normal I still have 5 psi of control.

ps I know I've got a minor boost leak btw

 

[numlock666]

Ok, I've read the first page of this thread so far and I'm setting this strait. Apparently you dont know how boost control happens.

First let me start off by explaining what the importance of a wastegate is. The wastegate is a bypass around the turbine. What turns your turbo? Exhaust. So lets put this scenario into play. Your engine takes in air, adds fuel, burns it, and the exhaust spins the turbine sucking in more air to be burned to spin the turbine faster. Thus and endless cycle. What the wastegate does is open up and alternative route for the exhaust gasses to go around the turbine, not letting it spin faster, thus controlling your boost. So when the wastegate actuater (brass looking thing with arm that goes from compressor side to turbine side) sees a 10lbs of pressure, the arm swings out and opens up the flapper inside the turbine housing (internal wastegate).

Now let me explain how the boost controller works. What it does is block pressure from getting to the wastegate acuator, thus not allowing it to open, thus increasing boost pressure. That is why when you run the actuator disconnected you get 30psi (infinite boost) because the actuator will never see 10psi to open up the gate. The MBC goes between the boost source (j-pipe) and actuator to block off the pressure by means of a spring and ball, but when the pressure behind the ball overcomes the force of the spring, the air is allowed past the MBC to the actuator, opening the wastegate.

So thats why you increase boost as you tightend the adjusting screw (increased pressure to block off the air to the actuator). Hopes this helps.

Also dieing turbos will still boost, Talesin knows that I know that first hand. My t-25, 14B, and my current B16G still boost and they are pretty much shot. Unless the shaft has snapped, or it has seized, it will boost, but efficientcy is the question.

 

[oldman]

From the pic it looks like the valve has been completely opened, or most of the way.. this would let air flow through the valve easier (or at a lower psi) and flow through to the wastegate actuator which would open at a lower psi, thus preventing more psi from building.. The way I understand it if you want a higher boost, you'd want to screw the valve down, so that a higher boost level can build before the MBC will let the air pass through to the wastegate.

Am I right oldman?

Yes, you're correct, at least in OP's case or for any BALL AND SPRING MBC's.

My MBC is a bleeder type valve and I set it close to all the way closed, like 3 turns from being closed fully. This gives me a nice 13psi of boost. If I open the valve I get less boost, if I close the valve I get more. No more than 15psi and no less than 10psi when taken to the extreme opened and closed positions. Dunno if thats normal I still have 5 psi of control.

No, that is not normal for a BLEEDER TYPE MBC, unless you're mistaking your ball/spring as a bleeder because it has a bleeder hole on it which all ball/spring MBC's do. Having only 5 psi of adjustment range usually means you have a light/weak spring.

ps I know I've got a minor boost leak btw

So what are you waiting for? Fix it.

 

[laserspeeddemon]

This is correct.

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This is correct.

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Now all you have to do is TURN THE SCREW IN!!! That will increase boost.

 

[ricktb]

ok heres a couple pics of my mbc, thats a bleeder no? Before I installed it I blew through it, as I turned it up (the +) more and more air went through like a water tap. As I turned it down it became increasing difficult to blow through and then until I can't at all..

I am planning to fix my boost leaks when I upgrade my IC piping and aftermarket bypass valve since my car is pretty much stock, and all the stock clamps leak, and the bypass valve leaks too. I tried to tighten the clamps more which helped, but I know they strip out eventually, and I'm close to doing that, besides my car runs so good now and holds 13psi steady can't complain.

ps I find to raise boost I turn it towards the - and to reduce boost I turn towards the + (kinda backwards but not if you understand what the valve represents)

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[oldman]

That is a different breed of bleeder mbc, haven't seen one of those in years, I actually had one of these (similar but not exact) while back but it has 3 fittings on it, do you have another fitting under the knob?

 

[oldman]

ricktb, I'm waiting for your answer so I can show you how to use (hook up) that controller properly, you definitely had it wrong.

 

[wishnfor4g63T]

Thanks all for the help especially oldman.

I came home today and played with the MBC. Right off the bat i turned it almost all the way in and begin my journey. started going over my limit at 15 so after the needle shot past that i would pull over and being turned the knob outward thus lowering boost. Few stops later i had turned it just right to 15 psi so . ATM i have it set to 14 pounds. BUT, i have another problem.

only at 14 pounds i have this problem and i had the same problem with my t-25. It feels like i'm shooting nerf balls outta my exhaust. As weird as it sounds it also feels like the turbo gets more air then lets off over and over thru out the rpm around 5k it smooths out and doesn't do it anymore (2nd and 3rd gears).

I'm still on stock fuel pump and injectors and know that if i push anymore than 13-14 pounds it would be to lean so i'm not going any farther.

Thanks again to everyone who helped i know now how boost controllers work and will definitly pass on my words to advice and help to anyone who needs it. THANKS THANKS THANKS

 

[oldman]

only at 14 pounds i have this problem and i had the same problem with my t-25. It feels like i'm shooting nerf balls outta my exhaust. As weird as it sounds it also feels like the turbo gets more air then lets off over and over thru out the rpm around 5k it smooths out and doesn't do it anymore (2nd and 3rd gears).

I'm still on stock fuel pump and injectors and know that if i push anymore than 13-14 pounds it would be to lean so i'm not going any farther.

I honestly have no clue what that means, you're going to have to do a better job on describing what's going on, I don't know what throwing Nerf balls out of your exhaust is suppose to feel like.

Thanks again to everyone who helped i know now how boost controllers work and will definitly pass on my words to advice and help to anyone who needs it. THANKS THANKS THANKS

No problem.

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ricktb, if you don't have another fitting on your MBC, hook it up and treat it as a "adjustable stock BCS".

1. Put a T (as close to the MBC as possible) on the pressure source coming off the compressor housing to the "inlet" of the MBC.

2. Connect the extra fitting on the T to the wastegate.

3. Connect the "outlet" of the MBC, the line you currently have going to the wastegate, to the little fitting on the intake pipe.

 

[wishnfor4g63T]

To better explain the problem.

It feels like shaftplay. Like the turbo is hitting the walls and rubbing then spinning freely then again to thit the walls. Only under 14 pounds does it feel right. I've checked the turbo for side to side and like i said it has a paper thin side to side i haven't really felt it for in and out so tommarow i will along with an oil change.

Yet this is just the feeling. It boost's fine doesn't slow down or nothing. If to explain this anymore it's almost like the turbo is bogging for a sec then going again but i swear it doesn't feel like the car is losing power at all. again this is only at more than 14 pounds. Without a FP and injectors i'm not going to push the turbo any harder.

 

[oldman]

To better explain the problem.

It feels like shaftplay. Like the turbo is hitting the walls and rubbing then spinning freely then again to thit the walls. Only under 14 pounds does it feel right. I've checked the turbo for side to side and like i said it has a paper thin side to side i haven't really felt it for in and out so tommarow i will along with an oil change.

Yet this is just the feeling. It boost's fine doesn't slow down or nothing. If to explain this anymore it's almost like the turbo is bogging for a sec then going again but i swear it doesn't feel like the car is losing power at all. again this is only at more than 14 pounds. Without a FP and injectors i'm not going to push the turbo any harder.

3 words, BOOST LEAK TEST!

 

[Talesin]

wishn, I do hope that you have an aftermarket boost gauge (though I don't think the stock 2G clusters even have numbers) to determine what level you're boosting at (if you have a 1G in addition to your 2G). If you have a boost gauge, it'd be good to put it into your car profile.

And yes, definitely boost leak test. Also bear in mind that the 14b flows more air than the baby snail t25, so you can hit fuel cut at a lower boost level, since the air is cooler and therefore more dense.

 

[kenamond]

I don't think anyone should be running above stock boost on an upgraded turbo without a logger. You wouldn't know until it was too late that you beat the snot out of your motor.